Despite the government's actions, YouTube was still widely accessible following the announcement.
Both sites have been used to publish leaks on corruption in the inner circle of PM Erdogan.
The latest move came hours after the release of an audio file on YouTube, purporting to be of a security meeting in which top government, military and spy officials discuss a possible scenario for military action inside Syria.
The bans come ahead of local and presidential elections.
Turkey's President and its courts have criticised the Twitter ban. Just yesterday, a court ordered a suspension of the Twitter ban.